Abstract: An air conditioning system controlled for automatically heating and/or cooling a multiple zone building is disclosed wherein each zone includes a zone temperature responsive load transmitter. Each load transmitter produces an output command signal for controlling operation of damper units and heating and cooling equipment. The command signal configuration is modified to avoid operation of heating and cooling equipment throughout a relatively wide "no load" band of zone temperatures centered around the zone set point temperature. The command signal is highly responsive to sensed zone temperature changes beyond the no load band so that the zone temperature tends to be maintained in the no load band.An alternative system is disclosed in which no load bands occur at two distinct command signal values and operation of damper units is effected when the command signal value shifts between the no load band values.